var person =Backbone.Model.extend({
	defaults:{
		name:"",
		sex:"",
		age:"32" ,
		score:120
	}

});
var man = new person();
man.on('change',function  () {
	console.log("change has happened");
});
man.on('change:sex',function  () {
	console.log("sex has be happened");
});
man.on("change:score",function(model,value){
	var oldscore = model.previous("score");
	if(value >oldscore)
		console.log(' 你比上次进步了'+(value -oldscore)+'分');
	else if(value < oldscore)
		console.log('你比上次退步了'+(oldscore - value)+'分');
	else
		console.log('你的成绩没有变化');
})
man.set("name","lokia");
man.set("sex","2"); 
man.set("score",200);
man.set({"age":"20","score":300});
